The invention relates to a disc brake for a commercial vehicle.
The clamping device of such a disc brake is pneumatically or electromechanically actuatable, wherein for this purpose the clamping device has a pivotable brake lever, which in the support region is embodied as a cam and, on the one hand, supports itself on a wall of the brake caliper and, on the other hand, on a displaceable bridge, for the purpose of which in the latter case a roller is positioned between the brake lever and the bridge.
For mounting the roller, a bearing shell which is configured in a circle-shaped arc in cross section is arranged in the brake lever, which is held in a trough-like seating of the brake lever, for example by riveting.
This bearing shell is designed as a so-called DU mounting, with a substrate, for example of steel, an intermediate layer of sinter material and a plastic coating, in order to obtain adequate sliding capability, which however, due to design-related history, is provided with a proportion of lead.
Under environmental aspects, the lead is considered problematic such that there are demands which aim at providing the bearing shell in a configuration which with respect to the material selection is not problematic.
Independently of this, milling out of the substrate material of the DU mounting occurs with the known bearing shell with increasing service life because of the numerous pivot movements of the brake lever, so that an optimized service life is not achieved.
Consequently, this leads to relatively high repair costs in order to continually ensure the operational safety of the disc brake. The costs resulting from this include the costs of the assembly and disassembly, the replacement part procurement, and the stoppage times of the vehicle for the duration of the repair.
These costs are incurred more or less independently of where the sliding bearing is arranged. The bearing shell, as mentioned, can be provided in the brake lever, where it then corresponds with a roller, which is connected to the bridge. It can also be provided on the bridge itself, with forming of a roller or a comparable bead on the brake lever. And it can be provided on the inside of a wall of the brake caliper, in the case of which for completing the sliding bearing the roller is likewise molded on or arranged as a bead on the brake lever. In this latter case, the replacement of the bearing shell proves to be particularly complicated and expensive because of the aggravated accessibility.
The invention is based on the object of further developing a disc brake of the generic type so that its service life, in particular that of the clamping device, is substantially extended with low expenditure in terms of design and production.
This object is solved through a disc brake in accordance with embodiments of the invention.
By this configuration of the arrangement of the bearing shell in the seating according to the invention, the bearing shell is practically clamped-in in the pivot direction of the brake lever so that, in contrast with the prior art, it cannot migrate beyond the original dimension. The described milling, as could be observed up to now, is thereby effectively prevented.
Here, the type of the stop edges, i.e. their shape, can be distinct. What is important is that a deformation of the bearing shell through the correspondence with the roller is practically excluded.
Besides these functional advantages, which lead to a significantly extended service life, from which a quite remarkable cost savings materializes, the modification of the new bearing shell compared with a known bearing shell is also significantly improved. This is especially due to the fact that DU sliding bearings can be employed, the sliding layer of which can practically make do without sliding addition.
The production of the bearing shell and not least its fastening in the seating prove to be significantly simplified since no rotation prevention needs to be provided any longer.
Since the bearing shell retains its original shape permanently, even after an operating duration that is far beyond what can be currently achieved, an exact guidance of the roller is always provided.
As has been surprisingly shown, the configuration of the sliding bearing according to the invention leads to a substantial increase of the relevant load cycle numbers, wherein very high load absorptions can be achieved with relatively favorable sliding bearing materials.
The stop edges are preferentially introduced into the long-side edge regions of the seating located opposite one another in a chip-removing manner and can be distinct in their design. Instead of a chip-removing design, the stop edges can also be realized in a casting method.
The cross-sectional shape of the stop edges can be present in the manner of a slot, possibly with minor demolding bevels, against which the bearing shell lies with edge-sided angled-off portions adapted thereto.
It is also contemplated to form the respective stop edge by a groove, in which a suitably formed edge of the bearing shell is held by flanging, crimping or clipping in place. Here, the groove can be embodied both angularly and also as a fillet that is round or non-round in cross section.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.